Oil economizing system for compressors



Feb. 23, 1943. w. R. FREEMAN ErAL OIL ECONOMZING SYSTEM FOR COMPRE SSORS Filed Nov.. 3,' 1941 K 4 5675 VI 2 I4 4 E M 44 v.4 4 MANA N T, j TMS R .O 3 FmEE w, T .-4. 1% mFF .9 RB M WC.

2 4 4 7 2 2 o Y 3 3 .B 22 2 Patented Feb. 23, 1943 OL ECON Oil/IIZIN G SYSTEM FOR COMPRESSORS Walter R. Freeman, Clay St. Johns, Mo.,

ton, and Cyril B. Fites, assignors to Wagner Electric Corporation, St. Louis, Mo., a corporation of Delaware Application November 3, 1941, Serial No. 417,602

(Cl. 23o-30) 6 Claims.

In a uid compressing system, such as one for air, and comprising a compressor, a storage tank, unloading valve, and a lubricating system, a considerable amount of lubricant, such as oil, is wasted by becoming mixed with the compressed uid and carried to the storage tank. 'I'his loss of oil,not only necessitates careful checking to ascertain whether the supply is sumcient, but also causes trouble as a result of its mixture with Water vapor to form a congealed mass which may easily prevent free dow of compressed air through the conduits.

One of the objects of our invention is to provide an improved oil economizing system for association with a compressor system which will extract the oil from the compressed air and return it to the oil reservoir prior to the entry of the compressed air into the storage tank.

A more specic object of our invention is to so associate an oil separating means with an air compressor system that the separated oil will be accumulated during the operation of the compressor and when the compressor is unloaded will be automatically caused to return to the oil reservoir through the same conduit which the compressed air passed to reach the separating means.

Other objects of our invention will become apparent from the following description taken in connection with the accompanying drawing in which Figure l is a view of a combined air compressor system and oil economizing system ernbodying our invention, parts being shown in section; Figure 2 is a sectional View of the principal oil separator; and Figure 3 is a sectional View of the combined unloading valve means and the oil dome venting valve means.

Referring to the drawing in detail, numeral I indicates the stator of a rotary compressor in which is reciprocably mounted a rotor 2 mounted on the shaft 3 driven by a pulley 4. rIhe rotor is provided with a plurality of circumferentially spaced blades (one only being partly shown in Figure 1). The shaft 3 of the stator is journaled in end plates 6 and 1, the end plate 6 being provided with the inlet passage 8 for the compressor. A casing 9 is secured to the end plate 1 to form an oil dome or oil reservoir I0 from which the compressor is lubricated. The o-il in this dome is under pressure and thus oil will be forced under pressure into the compressor for lubricating purposes. The means employed to conduct oil from the oil dome to the compressor comprises a conduit I I carried by the closure plate 'I opposite the end of the shaft 3 and extending down into the bottom of the reservoir. `The conduit communi- Cates with a passage I2 in the rotor shaft, which passage communicates with a slot I3 in the rotor to permit fluid to be conveyed to the different parts of the compressor. The rotary compressor, when in operation, will have chambers between the blades which are under sub-atmospheric pressure and this, in addition to the pressure on the oil in the oil dome, insures that there will be a sufficient now of oil into the compressor for all required lubricating purposes.

The end plate I is provided with the discharge passage I4 for the compressor, which discharge passage communicates with a tube I5 extending upwardly to a point above the oil level in the oil dome. On the end of this tube is mounted a preliminary oil separator I6 for removing the larger particles of oil from the compressed air, said particles being mixed with the air during the compressing operation. The large particles of oil are separated from the compressed air as a result of the compressed air being forced outwardly through the passages I'I and against the inner wall I8 of the separator. By causing the oil laden air to impinge on the walls, the oil will be separated and collect on said Walls from where it will run back into the main body of oil in the oil dome.

Compressed uid which has been discharged into the top of the oil dome after passing through the preliminary oil separator I6 is free to pass out through the passage I 9 associated with the top of the oil dome and to enter the conduit 20 leading to the main oil separator 2| which is so constructed as to remove substantially all of the remaining oil in the compressed air and particularly the mist and extreme small particles which were not removed by the preliminary oil separator The main oil separator 2|, which is shown in detail' in Figure 2, comprises an upright cylindrical casing 22 provided with a bottom member 23 having a central bore 24 to which is connected the conduit 2d leading from the oil dome. The connection between the conduit 29 and the bore 24 comprises a fitting member 25 having a central passage 26 leading to the bore and radial passages 2 leading to an annular chamber 23 formed by a groove in the fitting and the Wall of the bore. The inner end of the fitting through which the passage 26 extends has associated therewith a disc valve element 29 resting on the end of the fitting but free to be moved upwardly so that :duid can flow from the passage 25 to the bore by moving the disc upwardly and then passing around the disc through the slots Bil in the edge thereof.

The upper end of the bore 24 communicates with a tube 3| which extends upwardly through the cylindrical casing 2l to a point adjacent the top end Wall thereof. Secured to the upper end of this tube is an inverted cup-shaped member 32 having 'its cylindrical wall 33 surrounding the tube in spaced relation. Passages 34 at the upper end of the tube 3| permit communication between the tube 3| and the top of the cup-shaped member. The outer wall of the tube 3| is provided with a plurality of baffles 35 and the wall 33 of the cup-shaped member is also provided with bafiies 36. The baffles on the tube and member 32 are alternately arranged so that the iiuid which is discharged in the top of the cup-shaped member must pass back and forth between the baffles to reach the bottom of the cup-shaped member. Thus, by means of these bailies, it is seen that the direction of flow of the compressed fluid Ais changed a number of times and said compressed fluid as it flows around the baflles is caused to impinge upon a plurality of surfaces. Oil will be collected on these surfaces and then run down into the bottom of the cylindrical casing 22 of the separator. During the passage of the compressed air varound the baffles, some condensation of the -oil ,in the air also takes place, thereby aiding in the removal of the oil.

The compressed air, after passing the battles, will be free to pass out through the outlet passage 31 at the top of the separator `from where it may Venter the conduit 38 which leads to the storage tank (not shown). The outlet passage 31 has .associated therewith ra check valve 39 which is biased on itsseat by a light spring 40. This check valve does not lappreciably restrict flow of the compressed air from 1the separator to the tank but prevents any ,return flow.

The Ibottom 23 of the separator 2| is provided with a Ysecond bore 4| at one side of the bore 24. This :bore 4| communicates with the bottom of 'the cylindrical casing v'by a passage 42 and also with the annular chamber 28 by a passage '43. :Passage 42 has associated therewith a valve seat 44 and cooperating therewith is a check valve element 45 biased `onto the seat by a light spring 46 interposed between the valve element and the plug 41 :for closing the outer end of the bore 4|.

The inlet passage `8 of the compressor has associated therewith a combined unloading valve and dome venting valve generally indicated by the reference numeral 48. These valves have a single casing 49 which is mounted on the end plate 6. Within the .casing is an inlet passage 58 communicating with the angularly related passage 5| leading to the inlet passage 8 of the compressor. v AThe inlet 'passage '58 has associated therewith an air cleaner 52 (Figure 1). At the juncture of the passages 58 and 5| is a valve .seat 53 ,and cooperating therewith is a valve element 54 normally held Aoi the valve seat by a spring 55. The valve element 54 has apiston portion 55 which extends into a. chamber :51 where it can be acted upon by uuid pressure in said chamber. A conduit 58 places this chamber in constant communication with the conduit 38, previously referred to, leadf ing to the storage tank from the main oil separator 2 Thus, the air pressure in the chamber 51 is always the same yas that in the air tank. The piston head 55 of the valve is sealed by a diaphragm 59, the peripheral portion `of which is held sealed by a spring 58.

The casing 49 of the combined unloading and venting valve mechanism is also provided with a stepped Abore 81, the axis of which is at an acute :angle to the axis ofthe passage 5| and communicates with said passage by a passage 62. The shoulder 63 of the stepped bore has associated therewith a valve sealing ring 64 and cooperating with the ring is a piston 65 normally held off the sealing ring by a spring 65. The piston has an extension 61 provided with a conical end 68 forming a valve element for cooperation with a valve seat 69 formed on a closure plug 18 for the outer end of the stepped bore. This valve seat is associated with a passage 1| which communicates by a conduit 12 with passage I9 leading out of the top of the oil dome. The larger bore of the stepped bore is in constant communication with the passage 59 by way of a passage 13.

Between the passage 5| and the inlet passage 8 of the compressor there is provided a check valve 14 which prevents any air under pressure which might be developed by the compressor under certain conditions from being forced out through passage 5|. The check valve element permits substantial free iiow of air to the compressor.

Referring to the operation of the compressor, when the compressor is compressing air, the parts of the combined unloading and venting valve .mechanism will be in the positionsshown in Fig.- ure 3. The passage 1| will be closed and, therefore, the oil dome will be sealed. The valve element 54 will be maintained oi its seat by the spring 55. Thus, air under atmospheric pressure may be drawn through the air cleaner, passage 58, and passage 4|, from the inlet passage .to `the compressor where it will be compressed. During the compressing operation ,a certain amount oi oil in the form of mist andsmall particles will be mixed with the air and ybe .forced out with the compressedair through the discharge passage |4. This compressed air containing oil will pass through the conduit |5 and the preliminary oil .separator which, as .previously noted, will -cause vpart of the oil and particularly the large particles to be removed from the compressed air. The compressed air in the oil dome will also `act on the oil in the Areservoir to force oil .into the compressor in the manner already noted.

Compressed air, after entering the top portion of the oil dome, will pass through the outlet passage |9, the conduit 28 and into the main oil separator 2|. From here it will be caused to pass back and forth over the bailles where substantially all of the remaining oil mixed with the compressed air will be removed and collect in the .bot-

tom of the cylindrical casing 22. The compressed :air now free of oil will pass out through the check valve 39 and into the storage tank.

After the compressor has `operated a sufcient time to bring the pressure .in the storage tank up to a predetermined value, the unloading valve 54 Iwill be closed against the bias :of the `spring 55 vof predetermined strength. This closing is brought about by the `air pressure in chamber A51 which is in constant communication with the storage tank through the conduit 58. When the valve-element 54 is closed, air can no longer enter the compressor and, therefore, the compressor will cease its compressing operation and become unloaded. The continued rotation oi the compressor rotor, however, will cause a -sub-atmospheric pressure to develop in the inlet passage 8 and the passages 5| and 82. This will thus cause the piston 65 to be moved onto the sealing ring 64 due to the differential pressure acting on said piston. The .movement of the 'piston will open the passage 1| .and thereby place the dome in communication with the atmosphere by way of passage 13, passage 50, and the air cleaner. With air pressure relieved from the dome, no excess oil will lbe forced into the compressor during the unloaded period.

As long as there is air pressure in the dome, the valve element 45 at the bottom of the main oil separator 2l remains closed since the pressure on each side is equal and the spring 46 acts to hold the valve seated. When the dome becomes vented to atmosphere, the air pressure in passage 26, the annular chamber 28 and the bore 4l drops to atmospheric pressure. The air pressure in the main separator 2l, however, does not drop to atmosphere due to the fact that the disc valve 29 is seated by gravity. The super-atmospheric pressure remaining in the main oil separator will thus act to open the check valve element 45 and permit the oil which has accumulated in the' bottom of the oil separator to flow through passage 42, passage 43, annular chamber 28, passage 27, conduit 20, and passage i9 to the oil dome. When the oil is removed to the dome and the pressure in the separator is atmospheric, the valve element 44 rbecomes reseated. It is to be noted that the main oil separator should preferably be mounted above the top of the oil dome so that the oil will flow freely back into the oil dome when the Valve element 44 is unseated. However, this is not always necessary since there will be a high pressure in the main oil separator which can force the oil back into the oil dome.

When the pressure in the tank drops suiciently that the valve element 54 can be opened by spring 55, the compressor will again begin the compressing operation. When the suction is broken in passage I, the valve element 61 will be seated, thereby closing the dome to atmosphere.

Our oil economizing system has been found to be very eiiicient in operation. Substantially all of the oil is removed from the compressor before it enters the storage tank. Because of this it is not necessary to constantly be watching the oil level in the oil dome. Also, there is little danger of the tubes becoming clogged by a mixture of oil and water, The arrangement is also such that the oil which collects in the main oil separator will not be returned to the oil dome until the compressor becomes unloaded and then it is caused to be forced back into the dome under pressure. Thus, the conduit 2D through which the oil is returned to the dome, will always be cleared of oil so that there will be none left therein that can be forced back into the main oil separator when the compressor again operates to compress air,

Being aware of the possibility of modifications in the particular structure herein described without departing from the fundamental principles of our invention, We do not intend that its scope be limited except as set forth by the appended claims.

Having fully described our invention, what we claim as new and desire to secure by Letters Patent of the United States is:

l. An oil separating system for association with a uid compressor having an unloading valve and an oil reservoir associated therewith, said system comprising an oil separator having an oil accumulating chamber, conduit means for placing the separator in communication with the discharge outlet of the compressor to thereby convey the compressed fluid and oil carried therewith to the oil separator for separation of the oil thereby, a uid pressure outlet from the separator, conduit means for conveying the separated oil from the accumulating chamber to the reservoir, a

valve associated with the last'named conduit means for preventing oil from'returning to the reservoir, and means for causing said valve to be opened automatically when the compressor is unloaded by operation of its unloading valve.

2. An oil separating system for association with a uid compressor having an unloading valve and an oil reservoir associated therewith, said system comprising an oil separator having an oil accumulating chamber, conduit means for placing the separator in communication with the discharge outlet of the compressor to thereby convey the compressed fluid and oil carried therewith to the oil separator for separation of the oil thereby, a check valve fcr preventing compressed iluid returning from the separator to the compressor, a uid pressure outlet from the separator, a check valve for said outlet preventing return of compressed iluid, conduit means for conveying the separated oil from the accumulating chamber to the reservoir, a valve associated with the last named conduit means for preventing oil from returning to the reservoir, and means for causing said valve to be opened automatically when the compressor is unloaded by operation of its unloading valve to thereby permit the uid under pressure trapped in the separator to force the accumulated oil into the reservoir.

3. An oil separating system for association with a fluid compressor having an oil reservoir in which the oil therein is subject to the pressure of the compressed uid discharged from the compressor and also having Valve means for unloading the compressor and venting the reservoir to atmosphere, said system comprising an oil separator having an oil accumulating chamber, conduit means for connecting the separator to the reservoir above the oil therein to thereby convey the compressed fluid and oil carried therewith to the oil separator for separation of the oil thereby, and means for permitting the separated oil accumulated in the oil separator to now back into the reservoir only when the compressor is unloaded and the reservoir vented to atmosphere.

4. An oil separating system for association with a fluid compressor having an oil reservoir in which the oil therein is subject to the pressure of the compressed fluid discharged from the compressor and also having valve means for unloading the compressor and substantially simultaneously venting the reservoir to atmosphere, said system comprising an oil separator having an oil accumulating chamber, conduit means for connecting the separator to the reservoir above the oil therein to thereby convey the compressed iluid and oil carried therewith to the oil separator for separation of the oil thereby, and means for causing the fluid under pressure in the separator to act on the separated oil accumulated in fthe oil separator and force it back into the oil reservoir when said compressor is unloaded and the reservoir is vented to atmosphere, said means comprising a valve opened by a differential pressure created by venting of the reservoir.

5. An oil separating system for association with a fluid compressor having an oil reservoir in which the oil therein is subject to the pressure of the compressed fluid discharged from the compressor and also having valve means for unloading the compressor and substantially simultaneously venting the reservoir to atmosphere, said system comprising an oil separator having an oil accumulating chamber, conduit means for placing the separator in communication with the outlet of the compressor to thereby convey the compressed fluid and oil carried therewith to the oil separator for separation of the oil thereby, a check valve for preventing return iloW of compressed fluid from the separator, a compressed fluid outlet for the separator, a check valve for preventing return of compressed fluid through the separator outlet, conduit means for conveying the separated oil from the accumulating chamber to the reservoir, a valve associated with the last named conduit means and movable off its seat in the direction of the oW of oil from the accumulating chamber to the reservoir, said valve being subject to fluid pressure in the reservoir biasing it closed and opened automatically by the fluid pressure trapped in said separator when the compressor is unloaded and the reservoir vented Y to atmosphere to thereby permit the accumulated oil in the separator to be forced back into the reservoir.

6. An oil separating system for association with a fluid compressor having an oil reservoir in which the oil therein is subject to the pressure of the compressed fluid discharged from the compressor and also having valve means for unload-- ing the compressor and substantially simultaneously venting the reservoir to atmosphere, said system comprising an oil separator having an oil accumulating chamber, conduit means for connecting the separator to the reservoir above the oil therein to thereby convey the compressed iluid and oil carried thereby, a check valve associated with the conduit means for preventing return flow of fluid therethrough, an outlet from the separator for the compressed uid, a check valve for preventing return of compressed :duid through the outlet to the separator, means providing a conduit from the oil accumulating chamber of the separator to the rst named conduit means at a point between the check Valve therefor and the oil reservoir, and a valve associated with the last named conduit and opened by a differential pressure for permitting oil to flow therethrough from the separator back to the oil reservoir only when the `compressor is unloaded and the reservoir is vented to atmosphere.

WALTER R. FREEMAN. CYRIL B. FITES. 

